41 lines
1.3 KiB
GLSL
41 lines
1.3 KiB
GLSL
// pathfinder/shaders/gles2/xcaa-curve.fs.glsl
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//
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// Copyright (c) 2017 The Pathfinder Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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precision highp float;
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varying vec4 vEndpoints;
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varying vec2 vControlPoint;
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varying float vWinding;
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void main() {
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// Unpack.
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vec2 pixelCenter = gl_FragCoord.xy;
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vec2 p0 = vEndpoints.xy, p1 = vEndpoints.zw;
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vec2 cp = vControlPoint;
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// Compute pixel extents.
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vec2 pixelColumnBounds = pixelCenter.xx + vec2(-0.5, 0.5);
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// Clip the curve to the left and right edges to create a line.
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vec2 t = solveCurveT(p0.x, cp.x, p1.x, pixelColumnBounds);
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// Handle endpoints properly. These tests are negated to handle NaNs.
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if (!(p0.x < pixelColumnBounds.x))
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t.x = 0.0;
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if (!(p1.x > pixelColumnBounds.y))
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t.y = 1.0;
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vec2 clippedP0 = mix(mix(p0, cp, t.x), mix(cp, p1, t.x), t.x);
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vec2 clippedDP = mix(mix(p0, cp, t.y), mix(cp, p1, t.y), t.y) - clippedP0;
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// Compute area.
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gl_FragColor = vec4(computeCoverage(clippedP0, clippedDP, pixelCenter.y, vWinding));
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}
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